The present invention relates to a polycarbonate, more particularly to a polycarbonate having excellent flame retardancy and hydrolytic resistance and a resin composition containing the said polycarbonate.
Polycarbonates are widely used in many fields of industries as a resin with many advantageous properties such as high heat resistance, impact resistance and transparency. It is also known in the art that polycarbonates, although having relatively high non-combustibility among the known thermoplastic resins, lose their self-extinguishing properties when their molecular weight is enlarged. Recently, there is a demand for flame-retardation of the synthetic resin materials used for the commercial products, particularly OA equipment, home electric appliances and the like, and in order to comply with such demand, efforts are being made for the development of effective flame retardants.
Conventionally, halogen compounds or phosphorus compounds such as phosphoric esters and red phosphorus have been used preferentially for imparting flame-retardancy to polycarbonates. However, for obtaining excellent non-combustibility, it was necessary to blend a relatively large quantity of these flame retardants, which would lead to the disadvantage of impairing excellent mechanical and thermal properties inherent to polycarbonates.
On the other hand, as means for imparting flame-retardancy to polycarbonates by blending an additive or additives in a small quantity which won't affect the normal properties of polycarbonates, there have been proposed, for instance, a technique comprising blending an alkaline metal salt or an ammonium salt of perfluoroalkanesulfonic acid (DEP 1930257), and a technique comprising blending an alkali or alkaline earth metal salt of aromatic sulfonic acid (U.S. Pat. No. 3,948,851), but these resin compositions had the problem that their hydrolytic resistance is low.
For these reasons, those polycarbonates which themselves possess excellent flame retardancy or those which can be made flame-retardant with a smaller quantity of additive(s) have been required.